Contact tracing: a lesson from the Nipah virus in the time of COVID-19

Dear Editor

Over 2,954,222 confirmed cases and 202,597 deaths of COVID-19 have been reported globally by the World Health Organization (WHO). ¹ Without a vaccine or proven therapeutic options, the WHO recommends a combination of measures: rapid diagnosis and immediate isolation of cases; rigorous contact tracing; and precautionary self-isolation of close contacts to curb the spread of COVID-19. ²

During the Nipah virus (NiV) outbreak of 2018 in Kerala, India, rigorous contact tracing and precautionary self-isolation of close contacts successfully contained the outbreak to 23 cases in one single district. ³ NiV has an incubation period of 4–21 days and may present as two distinct syndromes or as a combination of acute encephalitis and respiratory system involvement. ⁴ During the second outbreak of 2019, it was confined to a single case in the district of Ernakulam. The authors were involved in the in-hospital contact tracing measures.

We reviewed all case details available from our hospital from the time of admission. Our contact tracing produced a list of 98 individuals who had come into contact with the patient in the four days since his admission, before he was diagnosed as having NiV and moved into isolation. A contact list was prepared through direct interviews in areas where the patient had been, use of internal communication measures such as email and circulars encouraging any staff to self-report, and the use of CCTV footage.

Contacts were asked to describe the nature of the contact event: touching the body; nursing; feeding; sharing the bed; sharing the room; cleaning body secretions/vomitus; or direct contact with coughing. Identified contacts were screened for symptoms and advised mandatory quarantine of 21 days. Any contact who developed a fever or symptoms was tested with oropharyngeal swab for reverse transcription polymerase chain reaction (RT-PCR) and serum samples for antibody testing.

Of the 98 contacts, further division into high-risk and low-risk contact was made based on the nature and duration of the interaction. Thirty-eight people were assigned as high-risk contacts while 60 were low-risk contacts. Seven people developed a fever during the quarantine period, but none tested positive on RT-PCR or serum antibody testing.

Reports of contact tracing for COVID-19 are highly reminiscent of that for NiV. With one patient producing a contact list of 98 in a healthcare setting, the implications in a community setting during a pandemic of the scale of COVID-19 are huge, but it proves that early and rigorous tracing with quarantining is an effective strategy to limit clusters. Currently, the burden of contact tracing falls on the public health authorities and the government. ⁵ Measures such as mobile applications that aid in contact tracing are increasingly being recommended, being developed by governments and sometimes even being made mandatory to hasten this laborious task.^6–8

We feel that contact tracing can be made more efficient if the general public is involved to a larger extent. We believe that if the public is encouraged to maintain their own contact list on a daily basis, it would help in significantly reducing the time and effort invested into contact tracing in the event of a person contracting COVID-19. Considering the urgent need for an effective contact tracing strategy in the containment of COVID-19, this cost-effective and non-resource-dependent method, even though never attempted before, could warrant a trial in these trying times.